1. Field of the Invention
The present invention relates to a vibration-type cantilever holder to fasten a cantilever having a probe in its leading end vibratably with a predetermined frequency and amplitude, and a scanning probe microscope having the vibration-type cantilever.
2. Description of the Related Art
As is generally known, an SPM (Scanning Probe Microscope) has been known as a device to measure a sample of a metal, semiconductor, ceramic, resin, macromolecule, biomaterial, insulator, etc. within a micro-scale area, and perform observation, etc. concerning physical property information including the viscoelasticity of a sample and the surface profile of a sample. As for such SPM, there are various measuring modes depending on targets for measurement. As one of them has been known a vibration mode SPM, by which measurement is performed by vibrating a cantilever set on a cantilever holder (see e.g. JP-A-2003-42931).
Such vibration mode SPMs include, for example: DFM (Dynamic Force Mode Microscope), by which scan is performed while the distance between a probe and a sample is controlled so that vibration amplitudes of the cantilever vibrated sympathetically are stable; VE-AFM (Viscoelastic AFM), by which the distribution of viscoelasticity is measured by detecting the amplitude, sine component and cosine component of bending of the cantilever when a sample is driven into small vibration in Z direction perpendicular to a sample surface or the cantilever is driven into small vibration in Z direction perpendicular to the sample surface thereby to apply a periodic force to the cantilever during the time of operation of AFM; and LM-FFM (Lateral Force Modulation Friction Force Microscope), by which the distribution of friction force is measured by detecting the amplitude of torsional vibration of the cantilever when a sample or the cantilever is driven into lateral vibration in a horizontal direction in parallel to a sample surface during the time of operation of AFM.
However, measurements by the above-described conventional vibration mode SPMs have problems as described below.
Usually in vibrating a cantilever, a predetermined voltage is applied to a vibration source mounted to a cantilever holder to vibrate the source, and then the vibration is transmitted to the cantilever, whereby the cantilever is made to vibrate with a predetermined vibration frequency and amplitude. However, the vibration of the vibration source also travels to surrounding structures other than the cantilever to vibrate the surrounding structures. These vibrations affect vibrational characteristics of the cantilever, and thus the vibrational characteristics are other than those of ideal vibrating state.
As a result, when measurement of Q curve (a curve showing sympathetic vibrational characteristics of a cantilever) is performed, other collateral sympathetic vibrations B, which are additional sympathetic vibrations, in addition to the sympathetic vibration A of the cantilever arise as shown in FIG. 7. As a consequence, the resultant characteristics includes vibrational characteristics coming from surrounding structures other than the cantilever, which makes it difficult to correctly discriminate the sympathetic vibrational characteristics of the cantilever. Therefore, in some instances it is difficult to make precise settings for vibrational characteristics of the vibration frequency, amplitude, and phase.
Further, in some instances, sympathetic vibrational characteristics of the cantilever are influenced when a probe is made to approach a sample, and thus the probe cannot be brought close to a measurement area, or the probe is brought excessively close to the measurement area, resulting in the collision with the sample because of the change in optimum measurement condition.
Still further, in some instances, sympathetic vibrational characteristics of the cantilever are influenced during the time of scan, and thus it becomes difficult to continue a stable and precise measurement because of the change in optimum measurement condition.